The present invention relates to a sealing structure of an outboard motor in which a top cowling is attached to a bottom cowling through a sealing material in such a manner that a bottom end of the top cowling covering an upper part of an engine is installed on an outer side of a top end of the bottom cowling covering a lower part of the engine.
As shown in FIG. 7, an outboard motor 100 is mounted on a stern plate 200 of a hull and has a propeller 101, which rotates by means of an engine 102 stored in a cowling 10, mounted on a bottom part thereof through a gear mechanism (not shown).
The cowling 10 comprises a bottom cowling 11 covering the lower part of the engine 102 and a top cowling 12 covering the upper part of the engine 102. The top cowling 12 is detachably attached to the bottom cowling 11. As shown in FIG. 8, a bottom end 12a of the top cowling 12 is attached on the outer side of a top end 11a of the bottom cowling 11 and a sealing material 20 provided between the bottom cowling 11 and the top cowling 12 tightly shuts an aperture between the two cowlings 11 and 12.
The sealing material 20 comprises: a cross-section roughly reversed U-shaped installation base member 21 fitted on the bottom cowling 11 by having the top end 11a of the bottom cowling 11 inserted in an opening thereof; a hollow seal member 22 which is fitted on an outer wall of the installation base member 21 and makes an elastic contact with an inner surface of the bottom end 12a of the top cowling 12; and a lip 23 projecting outward from an extending end which is a downward-extended part of an outer wall bottom end of the installation base member 21 so as to make an elastic contact with a bottom surface of the bottom end 12a of the top cowling 12.
The installation base member 21 has a plurality of projections 24 (FIG. 8 illustrates 4 projections) provided on an inner surface thereof and an insert 25 embedded therein to improve fitting strength of the installation base member 21 to the bottom cowling 11 so that the installation base member 21 does not easily come off the bottom cowling 11.
The above-structured sealing material 20 sufficiently seals a parting portion between the bottom cowling 11 and the top cowling 12 so that water cut-off performance thereof is improved because of the elastic contact made between the bottom end 12a of the top cowling 12 and the lip 23 as well as the hollow seal member 22.
In addition, the Japanese unexamined Patent Publication No. 2006-213152 discloses a sealing structure comprising a sealing material which tightly shuts the parting portion between the bottom cowling and the top cowling for the effect of the elastic contact of the hollow seal member, integrally molded with the cross-section roughly reversed U-shaped installation base member fitted on the bottom cowling, with the inside of the top cowling.
Said sealing structure of the Japanese unexamined Patent Publication No. 2006-213152 is characterized in that: the hollow seal member integrally molded with the installation base member fitted on the bottom cowling makes the elastic contact with the inside of the top cowling; and a splash preventive rib part is attached to an inner face of the top cowl, which extends downward around at least a majority of the periphery of the top cowl and positioned inside the top end of the bottom cowl.
Said structure prevents seawater which intrudes into the cowling from splashing in mist inside the cowling even if the hollow seal member does not sufficiently seal the parting portion.
The sealing material 20 shown in FIG. 8, however, may cause deterioration in sealing property when fitting dispersion changes a positional relation of the top cowling 12 toward the bottom cowling 11.
In another word, as shown in FIG. 9(a), when the top cowling 12 is attached to an inward position (bottom cowling 11 side) described in a solid line compared with a normal position described in a two-dot chain line, a top end of the lip 23 which makes an elastic contact with a bottom surface of the bottom end 12a of the top cowling 12 protrudes outside compared with the top cowling 12 so that sufficient sealing property is not performed and an external appearance deteriorates.
On the other hand, as shown in FIG. 9(b), when the top cowling 12 is attached to an outward position (opposite side to the bottom cowling 11) described in a solid line compared with the normal position described in the two-dot chain line, the top end of the lip 23 does not come into contact with the bottom surface of bottom end 12a of the top cowling 12 so that the sufficient sealing property is not performed.
In addition, the sealing structure disclosed in the Japanese unexamined Patent Publication No. 2006-213152 proceeds on an assumption that the sufficient sealing property can not obtained and intends to prevent the seawater which intrudes into the cowling from splashing by means of the splash preventive rib part. Therefore, said the sealing structure necessitates the splash preventive rib part as well as the sealing material.
Further, the sealing structure disclosed in the Japanese unexamined Patent Publication No. 2006-213152 does not take the fitting dispersion shown in FIG. 9 into consideration.
Therefore, an object of the present invention is to provide the sealing structure of the outboard motor, which deals effectively with the fitting dispersion and which is excellent in the sealing property as well as the external appearance.